112 A.P.COLEMAN — UPPJfiB AND LOWER lll'KOMA.N IN ONTARIO 



the jaspery rocks of the Michipicoton iron range. I have not visited the 

 point- myself, hut the specimens have heen brought in by prospectors. 

 How extensive these jasper bands are is not yet known. 



We do know, however, that jasper conglomerates form a very striking 

 part of the quartzitic rocks of the typical Huronian, and that pebbles 

 of jasper are met with more or less commonly in conglomerates as far 

 east as lake Temiscaming itself.* 



Source of Jasper Pebbles of the Huronian 



The source of these pebbles in the typical region on the shore of lake 

 Huron lias not yet been explained, since no bands of jasper have been 

 reported in the neighborhood. Possibly they are concealed beneath the 

 extensive lacustrine deposits of the region or are sunk below the waters 

 of lake Superior or lake Huron. From the widespread and abundant 

 occurrence of these jasper pebbles we may infer a source of considerable 

 extent. They can hardly have been obtained from the underlying Lau- 

 rentian, for jasper has never been reported from the Canadian Laurentian; 

 and since the jasper pebbles are in many cases distinctly stratified and 

 are associated with black chert pebbles, we must suppose them to be of 

 sedimentary origin, and so excluded from the Laurentian, employing 

 that term in the usual sense of a complex of ancient eruptive rocks now 

 more or less schistose. 



It is true that ferruginous chert is reported by Irving and Van Hise 

 from the Marquette region, associated with the Kitchi schist, which they 

 include in the Basal complex, but those authors are of opinion that the 

 small deposits referred to are in reality of vein formation, and therefore 

 later in age than the schist which incloses tliem.f 



One is tempted to ask if these cherty deposits are not more probably 

 remnants of the lower Huronian nipped into the Laurentian. The green 

 Kitchi schists themselves would probably be placed by Canadian geol- 

 ogists in the Keewatin or lower Huronian rather than in the Basal com- 

 plex or Laurentian. 



The most important Break in the Huronian 



Van Hise, the Winchells, and other American geologists who have ex- 

 amined the typical Huronian area are of the opinion that a break occurs 

 in the series between Logan's upper and lower slate conglomerates, just 

 above the main band of limestone, and that this is probably the equiv- 



*Geol. Can., L863, pp. 52 and 50. 



f U. S. Geol. Sur., monograph xxviii, Marquette Iron Bearing Dist., pp. 186, 187. 



